Help with duckling, please!

HI! My name is Amber and I have 30 chickens, 27 chicks, 4 ducklings, and a bunch of Bunnies! We've been doing this for 2.5 years and we've had goats and sheep and we love our hobby farming! I have an almost 5 week old duckling that needs help. It appears to be blind (from the moment we got it) and I ordered 4 ducklings and 26 chicks from a hatchery. This duckling is the only one that would ever let you pick it up and now we are having issues. It started a week ago and every time the duckling drinks water it throws its head back and sometimes flips around the brooder. It eats just fine and I've been supplementing with vitamins and nutra Drench. Its been a week and I haven't seen much improvement. The duckling is otherwise "happy" it's alert and moves around. I don't know what else to do. I give the duckling Poly Vi Sol and I add Vit E and Selenium to pea treats. I worry that I may just have to put the duckling down because if it ever had access to swimming water it would drown. Anybody have any other ideas? May just be my special needs duck. I love that it's so friendly now and willingly eats out of my hands. I cant bring myself to get rid of it. Thanks for any imput! In the pictures as soon as she takes a sip of water her head goes straight back and stays backwards for sometime and sometimes she'll flip around the bin. I've separated her and brought her in the house.